Bifilar compound filaments of polyamides

ABSTRACT

Bicomponent filaments having a slight non-linear crimp are prepared by spinning a conjugated filament from polyaurolactam and a second linear, readily crystallizable homo- or copolyamide, stretching the filament, and then subjecting it to a heat treatment.

United States Patent Kubitzek et a1.

[ 51 May 23,1972

[541 BIFILAR COMPOUND FILAMENTS OF POLYAMIDES Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany [22] Filed: Jan. 26, 1967 [21] App1.No.: 612,047

[73] Assignee:

[30] Foreign Application Priority Data Jan. 28, 1966 Germany ..F 48283 Feb. 24, 1966 Germany ..F 48511 [52] U.S. Cl ..161/173, 161/177, 260/78, 264/168, 264/171 [51 Int. Cl. ..B29f 3/10, D02; 3/00 [58] Field of Search ..264/176, 171; 260/78; 161/ 173-179 [56] References Cited UNITED STATES PATENTS 3,118,011 1/1964 Breen ..264/DlG, 26 3,216,976 11/1965 Schwartz et 21.. ..260/78 L 3,271,837 9/1966 Ay et a1 ....264/D1G. 26 3,297,807 1/1967 Settele ..264/171 3,315,021 4/1967 Luzzatto ..214/177 FX 3,317,482 5/1967 Kunde et al. ..260/78 L 3,321,447 5/1967 Kunde et a1. .....260/78 L 3,343,241 9/ 1967 Grajjar ..264/168 X 3,365,873 1/1968 Matsumoto et a1... ...264/D1G. 26 3,399,108 8/ 1968 Olson ..264/168 3,361,701 1/1968 Polack et a1. ..260/32.6 3,412,156 11/1968 Ueda et al 260/584 X 3,505,165 4/1970 Kubitzek et al,.., ..161/173 3,511,749 5/1970 Ogata etal 161/175 3,526,571 9/1970 Ogata 161/175 3,551,271 12/1970 Thomas et a1. ...l61/150 3,562,093 2/1971 Grifiiths et a1 ..161/173 F ORElGN PATENTS OR APPLlCATlONS 984,919 3/ 1965 Great Britain ..264/DIG. 26 25,173 11/1965 Japan ..264/DIG. 26 669,990 1/1966 Belgium ..264/171 Primary Examiner.lay H. Woo Attorney-Huntley & Tyner [5 7] ABSTRACT Bicomponent filaments having a slight non-linear crimp are prepared by spinning a conjugated filament from polyaurolactam and a second linear, readily crystallizable homoor copolyamide, stretching the filament, and then subjecting it to a heat treatment.

5 Claims, No Drawings BIFILAR COMPOUND FILAMENTS OF POLYAMIDES The present invention relates to a process for the production from high molecular weight polyamides of bicomponent compound filaments having a slightly non-linear crimp.

The advantages of crimped synthetic filaments and fibers have been known for a long time. Mechanical processes for their production have also been known for a long time, as has been the production of synthetic filaments and fibers having a latent crimp by spinning together two (or more) components with different shrinkage tendencies to form so-called com pound filaments. These filaments are preferably spun in such a way that the individual filament components lie parallel to each other along the length of the filament. Core spinning is used, on the other hand, to prevent splicing of the compound filaments in cases where the components used do not adhere to any extent to each other.

Since compound filaments of polyamides do not tend to undergo splicing, they may be spun to form bicomponent filaments, i.e. with only two components, and in such a way that the two components lie side by side over the whole length of the filament. The use of only two components considerably simplifies the procedure and the said arrangement of components is also preferable over the core spun structures because it results in filaments having a better crimp.

It is well known that polyamide bicomponent filaments only acquire a sufficient crimp under load if at least one of the components is a copolyamide, and preferably is not isomorphous. In order to achieve sufficient differences in the shrinkages, this copolyamide component must be modified with a rather high proportion, as a rule over 30 percent, of a second monomer.

It is obvious that polyamide bicomponent filaments containing one component which is such a highly modified copolyamide have numerous disadvantages. These disadvantages are caused mainly by the low tendency of copolyamides to undergo crystallization when stretched, a feature of their proporties which necessitates additional relaxation operations involving supply of heat to produce a quasicrystallinity in the copolyamide component during or after stretching.

The low tendency of the copolyamide component which is used in excess for the purpose of obtaining sufficient crimp, to assume a crystaline form moreover results in bifilar filaments which have only a moderately stable crimp after brief overloading by about 1 g/den. This is due to the drgree of elasticity, of the load bearing copolyamide high shrink component being distinctly reduced by the modification compared with that of pure homopolyamides.

It is an object of this invention to provide bicomponent filaments of polyamides, consisting of a) a polylaurolactam component having a rel. viscosity 1 of 2.2 to 3.0 measured in a 1 percent by weight solution of m-cresol at +25 C. in an Ubbelohde viscosimeter and b) of a linear readily crystallizable homopolyamide component spinnable into filaments or a copolyamide component. In the bicomponent filaments consisting of polylaurolactam and the homopolyamide component, both components have the X-ray diffraction patterns corresponding to crystallizable, linear homopolyamides.

A further object of this invention is a process for the production of crimped bicomponent filaments of polyamides by spinning in conjugated form polylaurolactam together with a) a homopolyamide wich crystallizes easily and which can be spun into filaments, or with b) a copolyamide which has been modified by up to percent by weight, and the bicomponent filament so obtained is stretched and then subjected, if desired after it has been worked up into woven or knitted fabrics or cut up into staple fibers, to an after-treatment with hot water or saturated steam. These bicomponent compound filaments are obtained in crystalline form after spinning and stretching even without additional application of heat, and they have a high capacity for crimping under load even after a hot water or steam treatment. In particular, they are distinguished by the crimp imparted being very permanent.

The process according to the invention provides for the production of bicomponent compound filaments having a latent crimp which can be developed by hot water or steam, from high molecular weight linear polyamides, in which process polylaurolactam having a solution viscosity of 2.0 to 4.0 and preferably 2.2 to 3.0, measured in a 1 percent mcresol solution, is spun together with a homopolyamide which is readily spinnable from the melt, or with an isomorphous or non-isomorphous copolyamide which has been slightly modified, i.e. by l to 15 percent, and which undergoes crystallization during spinning and stretching, to form a two-component compound filament in which the two components adhere together side by side over the whole length of the filament. These filaments are then subjected to a simple stretching operation either at room temperature, or over a heated stretching mandrel or over a heated bar. They have a latent crimp which can be developed by hot water or steam. The process is preferably used for the production of bicomponent filaments in which the components ratio is between 25:75 and 75:25 parts by weight. A characteristic feature is that after the stretching operation at room temperature, both components show X-ray diffraction patterns which correspond to those of the homopolyamides. If stretching is carried out at temperatures of 20 to C., a heated stretching mandrel should be used at the upper end of this temperature range. The use of polylaurolactam thus enables bicomponent crimped filaments to be produced without additional fixing or relaxation operations for lowering the shrinkage or for producing a quasi-crystallinity. Suitable second components are any homopolyamides which, when spun on their own under those conditions of viscosity, spinning temperature, stretching etc. which are optimal for the production of the bicomponent filaments in question, differ in their shrinkage on boiling by at least 3 percent from one-component polylaurolactam filaments spun under the same conditions. Particularly suitable are polyamides of e-caprolactam, hexamethylenediammonium adipate, polyaminopelargonic acid, polyaminooenanthic acid and hexamethylene diammonium sebacate.

Polycaprolactam which has a relative solution viscosities of 2.0 to 4.0, preferably 2.0 to 3.2, is especially advantageous for use as the homopolyamide which crystallizes out well. The filaments are preferably stretched over a mandrel heated to 50 to C.

Suitable copolyamides which crystallize out well which may be used are copolyamides which melt above 150 C. and can be spun from the melt, and which contain at least 85 percent by weight of basic units of the formula wherein R denotes a hydrogen atom or an alkyl, cycloalkyl or aryl group and R denotes an alkylene, cycloalkylene or arylene radical, and 1 to 15 percent by weight of one or more structural units which differ from these basic units. The structural elements which may differ from the basic unit may correspond generally to the basic units indicated above, in which groups R, or R may contain hetero atoms.

Owing to the extremely low shrinkage on boiling of polylaurolactam filaments, practically any copolyamides of two or more w-aminocarboxylic acids and/or diamine dicarboxylic acids which can be spun from the melt can be used as the alternative second component. Particularly preferred are the cocondensates of such inexpensive compounds as caprolactam, hexamethylene diamine, adipic acid, terephthalic acid, sebacic acid and w-aminoundecanoic acid. The proportion of basic component in the cocondensate should be at least 85 percent in order that the filament should show sufi'icient crystallinity on stretching.

The ability of the filaments spun from copolyamides to undergo crystallization is evidenced by their X-ray difiraction patterns, both components showing, after stretching, the X- ray patterns corresponding to the homopolyamides.

The modifying component in the co-condensate can be varied in any way desired so that it is possible to obtain crimp filaments with different properties as desired. Thus, for example crimp filaments with high reversability, i.e. with large differences between the crimp in water and that in the dry state, are obtained by using as second component of the bifilar filament co-codensates which contain sulphonic acid groups. Examples of such co-condensates are those obtained by incorporating by condensation N,N-disulphoalkyl-alkylenediamines or N-monosulphoalkyl-alkylene diamines (Belgian Patents Nos. 659,392, 663,930 and 665,506). Bicomponent compound filaments which undergo drying easily with acid dyes are obtained by spinning polylaurolactam together with basic modified polycaprolactams which have been prepared from ammonium salts of dicarboxylic acids and polyamines (Belgian Patent No. 643,732).

it is thus possible to vary the properties of the crimp filaments and to adapt them to the particular need in a very simple way be combining polylaurolactam with different slightly modified copolyamides. The properties of the compound filaments can, in addition, be influenced by the viscosities and the percentages by weight of the bicomponent components.

The bicomponent filaments obtained by the process can be used in the production of stockings, knitted and woven textiles, carpets and furnishing or lining fabrics.

The filaments are always worked up before they are crimped, and crimping is carried on the article before finishing processes are carried out. The following examples illustrate in more detail the invention:

EXAMPLE 1 Polylaurolactam having a relative solution viscosity of 2.4 in 1 percent by weight m-cresol solution, and polycaprolactam having a solution viscosity of 2.68 measured under the same conditions, are melted separately and metered through spinning pumps so that the two melts are supplied to a bicomponent spinning nozzle in a proportion by weight of 40:60. The filaments, which comprise the two components, the cross sections of which are shaped like the letter D, but are of different size, adhered together, are spooled at a rate of 700 m/min after passing through an air shaft at 25 C. at a crude titre of ISO/l2 den, the filaments are then stretched at a rate of 600 m/min in the ratio of 1:3.4 at 20 C. and 65 percent relative humidity.

In order to determine the crimp parameter, a strand produced from the stretched filaments is put under a load of 0.2 g/den and the length (a) is measured. The weight is then replaced by a second weight which only puts a load of 0.65 mg/den on the strand, and this loaded strand is then dipped in water at 95 C. in such a way that the load does not diminish at any time. After 5 minutes, the strand is removed from the water bath and its length is measured after drying for 24 hours at 22 C. and 50 percent relative humidity (G). The strand is then again loaded with the first weight and its length (6) again determined. The crimp elongation (c b)/b- 100 95 and the shrinkage on boiling (a c)/a 100 9 is thus obtained from the lengths a, b and c.

In order to determine the amplitude and length of the individual crimps, the filaments which have been brought to the state b are projected under specified conditions of enlargement on to white paper and measured. The following average values are obtained for the filaments of this example: Amplitude of crimp: 0.3 mm, length of each crimp: 0.5 mm.

EXAMPLE 2 Polylaurolactam of relative solution viscosity 2.45 in l percent m-cresol solution, and polyhexamethylene adipamide of relative solution viscosity 2.7 were spun to form compound filaments using the procedure described in Example 1. The ratio at which the two polyamides were spun was 45:55 and the spinning velocity 300 m/min. The filaments of crude titre 600/9 den developed an intense and voluminous crimp in boiling water after they had been stretched by 1:4 over a stretching mandrel heated to 150 C.

EXAMPLE 3 Polylaurolactam (n =2.38) and poly-7-aminoheptanoic acid (1;, =2.6)were spun at a ratio of 35:65 and spinning velocity of 600 m/min to form bicomponent compound filaments of crude titre 105/9 den and stretched in a ratio of 1:3.3 over a stretching mandrel heated to C. When treated with boiling water under a load of 0.2 mg/den, the filaments developed a voluminous crimp after drying.

EXAMPLE 4 Polylaurolactam having a relative solution viscosity of 2.40 measured in 1 percent m-cresol solution and a co-condensate of 90 percent by weight caprolactam and 10 percent hexamethylenediammonium terephthalate having a relative solution viscosity of 2.74 measured by the same method are melted separately and metered by spinning pumps in such a way that the two melts are brought together in a bicomponent spinning nozzle in a proportion by weight of 40:60. The filaments, which are spooled at 700 m/min and have a crude titre of 150/12 den, are then stretched at a rate of 600 m/min in the ratio of 1:3.4, under normal atmospheric conditions.

In order to determine the crimp parameter, a strand made from the stretched filaments is loaded with 0.2 g/den and the length (a) is measured. The weight is then replaced by a second one which only loads the strand by 0.65 mg/den, and the strand loaded in this way is dipped into water at C. in such a way that the load does not diminish at any time. After 5 minutes, the strand is removed from the water bath and its length (b) is measured after drying for 24 hours at 22 C. and 50 percent relative humidity. The strand is then again loaded with the first weight and its length (0) again determined. The lengths a, b and c are used to determine the crimp elongation (c b/b) lOO= 200 and the shrinkage on boiling (a c/a)' =18 percent.

In order to determine the amplitude and length of each crimp produced, the filaments treated up to stage b are projected in a specified manner under conditions of magnification on to white paper and measured. The following average values are obtained for the filaments of this examples:

Amplitude of crimping 0.15 mm. Length of each crimp are 0.20 mm.

EXAMPLE 5 Polylaurolactam having a relative solution viscosity of 2.38 and a co-condensate of 90 parts by weight of hexamethylenediammonium adipate and 10 parts by weight of hexamethylenediammonium sebacate having a relative solution viscosity of 2.5 are spun according to the procedure described in Example 1 to produce bicomponent filaments in which the components are present in a ratio of 1:1, The filaments, which have a crude titre of /12 den, are then stretched to 123.5 over a stretching mandrel heated to 90 C. The following crimp parameters are obtained by the method described in Example 1.

Crimp elongation 80% Amplitude of crimping 0.35 mm. Length of each crimp 0.80 mm.

EXAMPLE 6 Crimp elongation l20% Amplitude of crimping 0.4 mm.

Length of each crimp 0.8 mm.

EXAMPLE 7 Polylaurolactam of relative solution viscosity 2.48 and a cocondensate of 90 parts by weight of caprolactam and 10 parts by weight of w-aminoundecanoic acid of relative solution viscosity 2.50 are spun as described in Example 1 to form filaments which have a crude titre of 72/1 den which are then stretched to l :4. When the filaments are spun at equal delivery rates, i.e. with their respective D-shaped components having the same surface area, the following crimp parameters are obtained, determined as above:

Crimp elongation I 150%, Shrinkage on boiling l 1%, Amplitude of crimping 0.4 mm. Length of each crimp 0.7 mm.

EXAMPLE 8 Molten polylaurolactam having a relative solution viscosity of 2.36 in 1 percent m-cresol solution and a molten co-polyami of 98 and 2 percent w 3 (CH2)3 N(CH3) (CH2)6N(CH3) CH2)3 N 3- adipinate having a relative solution viscosity of 2.66 measured by the same method, were spun in a ratio of 45:55 to produce bicomponent filaments in which the components lay side by side. When they had been stretched by 1:35 at normal atmospheric conditions and dipped in hot water and dried, these 3.75 den filaments had the following crimp parameters:

Crimp elongation Length of each crimp 0.5 mm.

Amplitude of crimping 0.2 mm.

EXAMPLE 9 Polylaurolactam shavings having a relative solution viscosity of 2.40 in 1 percent m-cresol solution, and shavings of a cocondensate of 90 percent laurinlactam and 10 percent caprolactam having a relative solution viscosity of 2.38 were melted separately and spun at the rate of 800 m/min into bicomponent compound filaments of crude titre 205/20 den. These filaments, in which the components were present in the proportions of 70:30, had the following crimp parameters after they had been stretched by 13.2 under normal atmospheric conditions and treated with hot water:

Crimp Elongation Length of each crimp 0.35 mm.

Amplitude of crimping 0.1 1 mm.

We claim:

1. A bicomponent filament of polyamides consisting of a. a polylaurolactam component having a relative solution viscosity of 2.2 to 3.0 measured in a 1 percent by weight solution in m-cresol at 25 C. in an Ubbelohde viscometer; and

b. a linear, readily crystallizable, spinnable, homopolyamide of ca rolactam. 2. The icomponent filament of claim 1 in which the ratio of component azb is in the range of 25:75 to 75:25 by weight.

3. The bicomponent filament of claim I in which the relative solution viscosity of the caprolactam is 2.0 to 4.0 as measured in claim 1.

4. The bicomponent filament of claim 1 in which the relative solution viscosity of the polycaprolactam is 2.0 to 3.2 as measured in claim 1.

5. The crimped bicomponent filament of claim 1. 

2. The bicomponent filament of claim 1 in which the ratio of component a:b is in the range of 25:75 to 75:25 by weight.
 3. The bicomponent filament of claim 1 in which the relative solution viscosity of the caprolactam is 2.0 to 4.0 as measured in claim
 1. 4. The bicomponent filament of claim 1 in which the relative solution viscosity of the polycaprolactam is 2.0 to 3.2 as measured in claim
 1. 5. The crimped bicomponent filament of claim
 1. 